I'm sorry you are experiencing this very sad situation.
The reality is the mental programming they have received lives in the subconscious area of their mind and it is more powerful than anything you can say to them. Sad but true.
That programming is automatic to them and doesn't matter if one day all the governing maggots were charged with capital murder. Your parents would come to believe they were framed. Yes, the programming is that strong. Which is why they write about remaining "loyal to jehovah and his faithful slave." Their mind can no longer differentiate between God and the governing maggots. In their mind they are one in the same. This is why the maggots demand you attend the meetings, study, and participate before they'll even consider you for membership. The maggots know the power of group think and group pressure. The programming starts the moment that book study starts in our home.
Personally, I've shed many tears and had arguments with my spouse over her inability to see the maggots for the pieces of crap they truly are. After several years of studying how a person can be programmed I now understand my spouse cannot help but act the way she does. It's heartbreaking being that I still live with her. But I know I'm fighting something that is deeply ingrained and may never change.
I wish you and hope for the very best in your situation. It will get tough, but stay strong mentally and weather it out and see it through. YOU ARE RIGHT. THEY ARE WRONG.